| I've built a few cabs. It isn't exactly lutherie, but it does involve some wood working skills and it did lead me toward building my own bass eventually (after making some furniture).
I prefer Perfect Box design software, at least it seems to have worked well on the few cab's I built. Mostly I liked the modeling of the low frequency roll off. Sadly I cannot find a copy right now. Perhaps one of the other TB members will be able to dig up a copy.
You will likely get recommendations for other speaker cab design software. WinISD comes to mind. Use what works best for you.
A lot of 2-10" cabs roll off at 60hz and below. Not a big deal in my opinion, especially with a fretless bass, but a concern to many. Good luck!
- Paul | 
